The present invention relates to tobacco smoke filters incorporating a smoke-modifying flavor which in use becomes entrained in the smoke passing through the filter, and more particularly to a system for monitoring and adjusting the degree of flavor incorporated in the filter in order to maintain the amount of flavor within prescribed limits.
Flavoring compounds are incorporated into cigarette filters to produce flavored filters that are used to produce flavored cigarettes. It is important to monitor the amount of flavor added to the filter so that the cigarette taste remains generally consistent. In the past, methods such as weight and gas chromatography have been used to determine the amount of volatile flavor compounds in a given flavor substance.
In many instances filter samples are weighed by an operator to determine the amount of volatile flavor compounds that have been added to the filter. Such methods require many filters, usually twenty five to be weighed at one time in order to notice any change in the weight. Results may be adversely effected by moisture or the particular composition of the flavor.
Flavoring liquid used to flavor filters is generally made by dissolving flavoring constituents into a liquid solvent. If the amount of solvent or constituents varies from one batch of flavor to the next, the weight method for determining flavor change is not very accurate. Also, such weight methods cannot detect if only a few filters have non-consistent flavor amounts because the weight method takes the average weight of filters.
Gas chromatography is also used to determine the amount of flavor in cigarette filters. It is a cumbersome process that involves extraction of compounds from the filters and then performing chromatography which involves separation of the flavor composition components. Gas chromatography requires several hours and even days to determine the test results. Also, many volatile components escape during this process. Headspace gas chromatography helps to some extent. Gas chromatography usually requires at least three filters to obtain one reading. Again, variation in one filter would be averaged or masked.